Quantum Sensing Of Mitochondrial Function

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Mitochondria are small bacteria like organelles contained inside everybody's cells. Often called the battery pack of a cell, they are responsible for taking the oxygen we breathe and using it to generate a molecule known as ATP, the unit of currency for energy production inside most living organisms. Mitochondria generate ATP using chemical reactions that push protons to one side of a small membrane inside the mitochondria. This generates an imbalance of electrical charge across the membrane called mitochondrial membrane potential (MMP), equivalent in strength to the electrical field required for a bolt of lightning to strike during a thunderstorm. This charge imbalance inside the mitochondria pushes protons back through a small protein motor on the membrane to generate ATP, giving cells the energy required to function in their day-to-day tasks. The importance of this little organelle should not be understated and it is widely held to have underpinned the evolution of all complex life on earth. Dysfunctional mitochondria can cause many problems for health and have been linked to a range of diseases such as Parkinson's, heart disease, cancer and obesity. A by-product of this energy creating process in mitochondria are molecules called free radicals. The presence of free radicals inside the body are commonly thought to be a bad thing. It is true that in some circumstances they cause damage to the body however, these free radicals are also involved in many different processes in the body that are vital for the maintenance of health. As such free radicals have to be carefully regulated such that they are not being produced at harmful levels, but in sufficient amounts to allow cells to function normally. Collectively, this balance of free radical production and MMP is referred to as the mitochondrial redox state. This redox state can be a very good indicator of whether a cell is healthy or is undergoing stress or dysfunction. For example, a hallmark of many cancers is 'the Warburg effect' in which cancer cells have a very different mechanism for generating energy which implies a change in the function of mitochondria in growing tumours. Researchers have long been interested in how to better understand mitochondria. However, the technologies we use today have certain limitations; one example is the toxic side effects of different chemicals and invasive probes used to measure MMP. In this work we will develop a new technology that can non-destructively study mitochondria more accurately than existing methods to increase our understanding of these organelles and help develop treatments for diseases more effectively. Our approach is based on a peculiar property of pink diamond that will allow us to use a light microscope to study MMP and free radical production in living cells. Pink diamonds obtain their pinkness due to the presence of Nitrogen impurities lodged in the diamond's usually pure carbon structure. These impurities absorb green light and re-emit red/pink light. Physicists have discovered in the last 10 years that the intensity of this light can be used to measure electromagnetic fields very accurately (~250,000 times smaller than the electric field present in mitochondria) and at very short length scales (about 1 million times smaller than the width of a human hair). Our proposed work involves patterning very thin slabs of diamond with a uniform surface layer of these impurities. Then using a series of controlled pulses of green light, we can take pictures of the red/pink fluorescence using a camera and reconstruct a spatial heat map of electric fields and free radicals produced by mitochondria in cells growing on the diamond surface. We predict this new technology could overcome many of the disadvantages of currently used techniques, and will be able to provide new information about how mitochondria work. This could then lead to new and effective treatments for different diseases for the benefit of all.